Recent research has shown a higher risk of autism with exposure to traffic related air pollution and a new study showed a lower risk of autism with increased amounts of green space, specifically tree cover when there was high road density. (Lucio G. Costa, Yu-Chi Chang, Toby B. Cole, "Developmental Neurotoxicity of Traffic-Related Air Pollution: Focus on Autism," Current Environmental Health Reports 4, no.2 (June 2017): 156-165, doi:10.1007/s40572-017-0135-2; Jianyong Wu, Laura Jackson, "Inverse Relationship Between Urban Green Space and Childhood Autism in California Elementary School Districts," Environment International 107, (October 2017): 140-146, doi:10.1016/j.envint.2017.07.010). The latter study included autism prevalence in 543 of 560 public elementary school districts in California. Besides air pollution, noise may also be a factor. Both children with autism and individuals exposed to high levels of traffic related air pollution exhibit elevated levels of inflammation, including in the brain. In individuals who are genetically susceptible to autism, air pollution may be a contributing factor. For this and many other reasons, life may be easier by going green.